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Wind Lantern 



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Wind Lantern 



Written By: Dustyn Roberts 



f TOOLS: 



Deburring tool (1) 
and/ or a rounded file 

Hacksaw (1) 

Hex keys (1) 



© PARTS: 



Stepper motor (1) 

Breakaway male headers (1) 

Solderless breadboard (1) 

Jumper wires (1) 

Diodes (8) 

LED(1) 

Capacitor (1) 

Acrylic sheet (1) 

Aluminum flashing (1) 

Shaft collars (1) 

5mm bore with set screw 

Shaft collars (7) 

1/2 in bore with set screws 

Aluminum tube (1) 

1/2 in outer diameter - 18 in length 

Flanged sleeve bearing (2) 
1/2" shaft diameter 

Thrust bearing cage assembly (1) 
for 1/2 in shaft diameter with two 



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Wind Lantern 



matching washers (McMaster 5909K44) 

Threaded standoffs (3) 

4 in length, 1/4 in -20 screw size 

Cap screws (6) 

socket head 1/4 in -20 thread 3/4 in 

length 

Lock washer (6) 
for 1/4 in screw size 

Flat washer (6) 

for 1/4 in screw size 

M3 screws (4) 
40mm long 

M3 lock washers (4) 

M3 washers (4) 



SUMMARY 

In this project, we'll build a small, vertical-axis wind turbine, or VAWT for short. These are 
not as efficient as their horizontal-axis cousins, but they are better suited to urban 
environments where wind can come from all different directions. 

Normally, when you give electricity to a motor, it spins. The same is true in reverse: If you 
give a motor a spin, it acts as a generator and creates electricity. The wind lantern will use 
energy from the wind to turn a motor and the resulting energy to light up some light emitting 
diodes (LEDs) within the base. The wind lantern will use this electricity to create a flickering, 
glowing indicator of the wind. 

LEDs, like any other diodes, allow current to flow through them in only one direction. Bipolar 
stepper motors have two wire coils. The challenge here is to design a circuit that directs 
energy generated in each coil through an LED in the correct direction, no matter which way 
the wind lantern spins. To do this, we'll build a rectifier circuit for a bipolar stepper motor. 

You can download the FREE template here on Thingiverse , or go ahead and buy them from 
my Ponoko showroom . 



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Wind Lantern 






Put on your safety glasses and cut an 18" length of the aluminum rod with a hacksaw. Use 
a deburring tool or file on the inside and outside of the end of the rod to smooth it and avoid 
cutting yourself. 

Make sure your aluminum rod fits through the flanged sleeve bearings, thrust bearing and 
washers, and the shaft collars. Look at the tolerances of all the parts on McMaster: 

• The aluminum rod has a ±.025" outer diameter tolerance, which means it can range 
from 0.475" to 0.525". The shaft collars don't give a tolerance for their inner diameters. 
The flanged sleeve bearings say +.001" to +.002" for the inner diameter. This means 
they will be between 0.501" to 0.502". The thrust bearing says 1/2" +0.002" to +0.007", 
which means the inner diameter can range from 0.502" to 0.507". The thrust washers 
don't give any tolerance for the inner diameter. 

This means that the outer diameter of the aluminum rod needs to be smaller than the 
smallest possible part it needs to fit into, which is the 0.501" sleeve bearing. As you can 
see here, we have a good possibility for overlap in an inconvenient direction. 

If your aluminum rod is too big for the sleeve bearing, put on your safety glasses, dust 
mask, and gloves (aluminum dust is not good for you). Grab the aluminum rod with the 
sandpaper and rotate it while you're squeezing until you see aluminum dust coming off. 
Continue this until the rod fits through all the components. If you're lucky enough to have 
access to a lathe, it could be a time-saver if you have a lot of aluminum to shave off. A 
bench grinder will work faster than sanding by hand, but it will be harder to maintain the 
round shape of the rod. 



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Wind Lantern 





• Assemble the base (refer to the full 
picture as you go through the 
steps). Start with the two disks, the 
hex standoffs, and the 1/4-20 
screws, lock washers, and 
washers. Install the standoffs by 
sandwiching the acrylic disk, a 
washer, and a lock washer on each 
end with a 1/4-20 screw. 



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Wind Lantern 




• Install one of the flanged sleeve bearings in the center hole of the base disk. The base is 
the one without the four holes to mount the motor. 

• Rest a thrust washer, thrust bearing, and then the other thrust washer on top of the flange. 

• Slide the aluminum rod in from the top. Before it hits the sleeve bearing on the bottom, it 
should slide through the other sleeve bearing, a 1/2" shaft collar, a laser-cut gear, two 
more 1/2" shaft collars, and finally the thrust washer, bearing, and washer stack. 

• Pull up slightly on the aluminum rod so it's not hitting your work surface. Use your Allen 
key set to tighten the set screw in the lowest shaft collar. At this point, the shaft collar is 
resting on the thrust bearing and attached to the aluminum rod, so you should be able to 
spin the rod. 

• Lift the next shaft collar from the bottom up with the gear to about the halfway point inside 
the base. Tighten the set screw. This shaft collar will be attached to the gear with epoxy 
putty later, but DO NOT do this yet. 



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• Secure the top sleeve bearing with 
the top shaft collar. 



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Wind Lantern 





• Before you continue up the rod, this 
is a good time to mount your motor. 
First, cut the wires to about 8" long 
and solder a set of four male 
headers to the wires. Red and 
green should be next to each other 
on one side, and blue and yellow on 
the other. 

• Remove the screws that hold the 
motor together. Use the longer M3 
screws from the shopping list to 
mount the motor from the back, on 
the underside of the top disk. 
Sandwich an M3 washer and lock 
washer with each screw. 

• Slide the other gear onto the motor 
shaft and use the 5mm shaft collar 
to secure it temporarily. Adjust the 
height of both shaft collars until the 
gears are at the same height and 
mesh well. Now you can break out 
the epoxy putty and secure the 
gears to their respective shaft 
collars. 



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Wind Lantern 




• Continue up the aluminum rod. Slide on a 1/2" shaft collar, one of the plastic sail holders, 
and then another 1/2" shaft collar. Pull the lower shaft collar up so it's not resting on the 
top of the base and secure it to the rod with its set screw. Then pinch the plastic sail 
holder with the shaft collar on top of it, and secure the assembly with a set screw. When 
you rotate the whole assembly by the shaft, it should rotate smoothly, and the sail holders 
should rotate with the shaft. 

• Cut out three sails for your wind turbine to catch the wind. There's no right answer here, 
and you have a few different slots in the sail holders, so just use scissors to cut the 
aluminum flashing in a length you think will work. Then cut 1/2" tabs into each corner to 
slide into the slots. Bend over the tabs to secure the sails. 

• Do the same shaft collar, sail holder, shaft collar assembly on the top of the sail to finish 
this section of the build. It should spin with very little friction when you turn it by hand with 
the aluminum rod. 



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Wind Lantern 




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We need to create a circuit like the 
one shown here. Use the eight 
diodes and jumper wires to create 
this circuit on your breadboard as 
shown. It will tell any electricity 
generated in each coil of the motor 
to go to the same place: the power 
column on the bottom of the 
breadboard. Make sure all your 
diodes are facing the right 
direction, and don't forget to jump 
the ground columns across the 
board. Here's a schematic too if 
that's easier. 

Notice the LED in the center and 
the two capacitors at the sides of 
the board. Plug the long leg of your 
LED into the power column and the 
short one into ground. Before you 
add the capacitors, give the wind 
lantern a spin and watch the LED 
flicker! 

Try adding at least one capacitor 
as shown. The negative marked 
side should go to ground, the other 
to power. The capacitor will store 
energy while the wind lantern is 
creating it, and release it when it is 
not. The resulting effect here is a 
smoother flicker on the LED. Try 
adding more LEDs and more 
capacitors until you get a smooth 
glow when you spin the aluminum 
rod. You can also place diffuser 
paper over the side of the lantern to 
create a pleasing glow. 



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Wind Lantern 





Now take it outside! See if it works 
with real wind. We had success on 
a street corner in Manhattan and on 
the roof of Eyebeam Art + 
Technology Center's two-story 
building. 

Thanks to awesome intern Sam 
Galison for helping with the project! 



This project appears in the book Making Things Move by Dustyn Roberts 



This document was last generated on 201 2-1 0-31 01 :27:44 AM. 



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